Belt construction and method of forming the same



J. R. WAGNER Nov. 1, 1966 BELT CONSTRUCTION AND METHOD OF FORMING THESAME 2 Sheets-Sheet 1 Filed Oct. 14, 1964 Fl.i

BELT TRAVEL Nov. 1, 1966 J. R. WAGNER 3,281,905

BELT CONSTRUCTION AND METHOD OF FORMING THE SAME Filed Oct. 14, 1964 2Sheets-Sheet 2 UHHUUHUUUHUHU-IO2 82 98 8 Q as 78 as United States PatentYork Filed Oct. 14, 1964, Ser. No. 403,769 11 Claims. cl. 24 s3 Thisinvention relates to belt constructions and more particularly relates topapermakers drier belts and to methods of forming the same.

Drier belts of the type to which the present invention is directed,while of general application, are particularly well suited for use inconnection with the manufacture of non-woven fibrous products such aspaper, paperboard, box-board, etc., in a papermaking machine. As is Wellknown, such machines customarily include a wet section and one or moredrying sections. The paper product is formed from a web ofwater-saturated pulp which is transported by one or more papermakers wetfelts through opposed press rolls and other dew-atering devices in thewet section of the machine until the moisture content of the web isreduced and its fiber structure compacted to such a point that it maybecome substantially self-supporting. The web is then received by one ormore drier belts which are arranged for movement along endless paths tocarry the web around a series of rotating drier drum or cans in thedrying section of the machine. These drums apply heat to the web toremove the remaining moisture.

Numerous arrangements are employed to fasten the ends of flat fabrics torender them useful as drier belts. In some cases the ends areover-lapped and sewn, riveted or glued together. In other situations theends are brought together in a butt joint and secured by a strip ofmaterial overlapping the joint. For the most part, however, the ends ofpresent day drier belts are joined by a clipper seam, which is a form offlexible hinge that includes a series of interleaved clipper hookclenched to the belt ends or to supporting fabrics sewn to the belt. Anelongated connector, customarily in the form of a cable, extends throughthe hooks to hold the ends of the belt in place.

All of the foregoing methods of forming a seam are relativelyeconomical. However, all produce a seam which is substantially differentfrom the remainder, or body, of the belt in regard to thermal expansionor contraction, moisture growth or contraction, residual shrinkage,resiliency (expansion or contraction under stress), permeability, heattransfer and similar qualities. These differences between the seam andthe rest of the belt may cause the belt to wrinkle and pucker whenplaced into service. That is, wrinkles and puckers appear due to thedifferential effect of temperature, moisture, stress and other factorson the seam as compared with the body of the belt, and this is ofspecial moment under the widely varying conditions encountered in thedrying section of a paper machine. For instance, under tension in themachine direction, or longitudinal direction, the belt tends to lengthenand become more narrow. The seam does not narrow to the same extent asthe body of the belt, causing wrinkles and puckers to appear. Thewrinkles and puckers may undesirably mark the paper web being dried.

It is known that endless belts may be produced wherein the seam isvirtually indistinguishable from the body of the belt, for instance, byspecial weaving processes, or hand interweaving of the ends of a flatbelt. However, these processes are expensive and increase the cost ofthe belt and also the cost of installing it on a paper machine.

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There is at present no known way of joining two ends of flat woven beltsby inexpensive means and methods without introducing the aforesaidundesirable properties.

One genera-l object of this invention is to provide a new and improvedfastening construction for the ends of a papermakers drier belt.

It is another object of the present invention to provide an economicalmethod of seaming flat belts by which the seam has substantially thesame thermal expansion or contraction, moisture growth or contraction,residual shrinkage and resiliency characteristics as the body of thebelt in the transverse direction, as well as good permeability, heattransfer, etc.

It is another object of this invention to provide a belt which has aneconomical seam construction in which the seam and the'body of the belthave substantially uniform characteristics in the cross-machinedirection as regard to thermal expansion or contraction, moisture growthor contraction, residual shrinkage, resiliency, permeability, heattransmission and the like.

It is another object of this invention to provide a papermakers drierbelt in which the sea-m, as well a the remainder of the belt, hassubstantially the same width during operation, thus substantiallyeliminating wrinkles, puckers, stresses and the like.

It is a particular object of this invention to provide an improvedclipper seam for a papermakers drier belt which has the same thermalexpansion or contraction, moisture growth or contraction, residualshrinkage, resiliency, permeability and heat transmissioncharacteristics as the body of the belt in directions parallel to theseam.

Other objects as well as features of the present invention will be bestunderstood by reading the present specification in conjunction with thedrawings, in which:

FIGURE 1 is a perspective view of a seam in a papermakers drier belt inaccordance with one embodiment of the present invention;

FIGURE 2 is a plan view of a seam in a papermakers drier belt showinganother embodiment of the present invention;

FIGURE 3 is a sectional view taken generally along the line 33 of FIGURE2;

FIGURE 4 is a fragmentary plan view of a drier belt utilizing anotherembodiment of the present invention; and

FIGURE 5 is a perspective view of another embodiment of the presentinvention showing the use of flaps in conjunction with a seam in thepractice of this invention.

The objects of this invention may be achieved by joining the ends of aflat woven fabric or other belt material by means of a plurality ofdiscrete seam segment spaced apart from one another successively acrossthe width of the belt. Desirably, the spacing between successive seamsegments is such that apertures between the seam segments substantiallydisappear during operation. Even where the intersegmental apertures donot close during operation, a paper web is not marked in anyobjectionable fashion during drying.

While in some cases the cooperating end segments are joinedindividually, it is highly advantageous to form a single continuous seamextending completely across the belt, in any of the usual manners, as byclipper hooks, stitching, gluing, riveting, etc., and to then divide theseam into segments by removing discrete portions of the seam atpredetermined intervals to form apertures between the segments. Theintersegmental apertures extend completely through the scam in thelongitudinal, or machine, direction and, desirably extend even furtherinto the body of the belt in both directions from the seam, say up toabout three inches from the seam. The Width of the seam segments dependson the width and construction of the belt but preferably is betweenabout 2 to 6 inches. The preferred width of each aperture is betweenabout inch and one inch. The apertures are preferably diamond-shaped,but there are several good embodiments in which the apertures aresubstantially rectangular in configuration. Other intersegmentalaperture shapes may be employed, and it is not intended to limit thescope of the broader aspects of the invention to any particularintersegmental aperture shape.

Papermakers drier belts vary in width from as narrow as four feet insome instances to as broad as thirty feet or more in other instances.The wrinkling and puckering which besets papermakers appears to be ofparticular significance in connection with wide belts of this type.

The division of the seam into a plurality of relatively narrow segmentsprovides a means by which diagonal stress, such as is generated byfabric non-uniformities, cocked rolls, etc., may be reduced inmagnitude. Diagonal stress will not be transmitted by the relativelynarrow seam segments to the same extent that it is transmitted by asingle large seam. Rather, the multiple seam segments distributecross-machine stress into the machine direction. In this manner,diagonal stresses are confined to narrow bands which conform to thewidth of the fabric segments between the apertures.

Wrinkling and puckering of the belt are eliminated by use of thesegmented seam. Apparently, the apertures between the segments tend tocompensate for differences in thermal expansion or contraction, moisturegrowth or contraction, residual shrinkage, stresses, resiliency, etc.,between the seam and the body of the belt in the crossmachine direction.It is believed that the intersegmental apertures permit thecross-machine dimension of the seam to contract or expand to conform tochanges caused by moisture, temperature, tension, etc., to substantiallythe same extent as the width of the body of the belt.

The intersegmental apertures improve the permeability and heat transfercharacteristics of the seams and cause such factors to closely approachthose of the body of the belt. The permeability at a seam in apapermakers drier belt is affected by the number and type of thicknessesof layers of the material of which the belt is composed, and variationsin permeability may cause paper marking. The permeability across theseam may be made to substantially equal the permeability in the body ofthe belt due to the size and arrangement of the apertures associatedwith the segmented seam. The effect on permeability is particularlyevident where the seam in the drier belt is made by folding the ends ofthe belt over on itself to produce a loop for connection purposes, forinstance, in a clipper seam. By employing the intersegmental aperturesof the present invention, the net permeability across the length of theseam may be maintained and paper marking due to that problemsubstantially eliminated. Also, the utilization of the segmented seamprovides a means by which the higher insulating qualities of a multiplelayered belt seam may be reduced, again probably due to the aperturesassociated with the seam.

The present invention may be applied to produce an improved clipper seamwhich is uniquely different from heretofore known clipper seams in thatit permits the seam to relieve stresses and to expand and contract,stretch and return, in the cross-machine direction as the body of adrier belt contracts or expands, stretches or returns in thecorresponding direction as the result of heat, moisture, tension orother environmental changes during operation. The improved propertiesenable the clipper seam to maintain approximately the same width as theremainder of the belt and to relieve stresses during operation.Therefore wrinkles, puckers, stresses and other non-uniformities in theseam or belt associated with clipper seams are reduced or eliminated. Itis believed that the desired result occurs because the clipper seamcable, being cut and therefore discontinuous or being in the form ofshort rods or pins, permits the seam to expand and contract, stretch andreturn and also allows the yarns of the belt to distort and thereforerelieve stresses, whereas the continuous seams of the prior art wererestricted in such motion by the continuous-type cables heretoforeemployed. The segmented seam of the invention permits the stress pointsin the belt and the seam, such as might be caused by machinemisalignment, roll deflection, moisture and thermal conditions, etc., toshift in accordance with the particular operating conditions and therebyavoid the appearance of wrinkles or ripples.

Drier belts in which polyurethane adhesive is used in the seam have agreater probability of causing wrinkling than many of the other knownseaming methods. The present invention also is applicable to seamsformed with polyurethane resin to reduce wrinkling and puckering.

It is known that, in the case of woven belts where the belt crossdirection yarns are formed from nylon, moisture absorption causes growthor linear expansion. By use of the present invention, the growth in thecross direction may act substantially uniformly in both seam and belt,thus preventing wrinkling and puckering due to that cause.

In several embodiments of the invention, the drier belt is of open weaveconstruction and is woven from synthetic yarns. In cases in whichadditional stability, shove resistance, etc., is desired, the wovenyarns preferably are treated with resins in a manner similar to thatdescribed, for example, in Holden and Schiif U.S. Patent 2,903,021,granted September 8, 1959, or in Beaumont and Christie U.S. Patent3,032,441, granted May 1, 1962. One particularly advantageous apparatusfor preparing the yarns is disclosed in Christie and Schiif U.S. Patent3,149,003 granted September 15, 1964.

In other arrangements, the drier belt may be of substantially anyconstruction consistent with good drying action, including conventionaldrier belts woven from yarns of cotton and asbestos or from syntheticyarns for example, or various perforate or imperforate non-woven belts,such as those of rubber or various synthetic film materials, etc.

Referring to FIGURE 1 of the drawings, there is shown a drier belt 10having typical seam segments 12 and 14. The terminal portions 16 and 18of the belt are folded back upon themselves to provide a doublethickness of material forming the seam segments 12 and 14. The foldedterminal portions are held in place by a suitable stitching 20, 22. Aplurality of clipper hooks 24 are clenched to the seam segment 12 andare arranged in interleaving relationship with cooperating clipper books26 similarly afiixed to the seam segment 14. The hooks 24 and 26accommodate a segmented cable 28 which extends in a transverse directionand serves to hold the ends. of the segments 12 and 14 in fixed butflexible relationship with each other.

Seam segments 30, 32, 34, 36, 38 and 40 are similarly comprised ofterminal portion, stitching, clipper hooks and cable. Seam segment 12 isdisposed opposite and cooperates with seam 14; similarly, seam segments30, 34 and 38 are disposed opposite and cooperate with seam segments 32,36 and 40, respectively. The adjacent seam segments 12 and 14, 30 and32, 34 and 36, 38 and 40 are spaced apart from one another by apertures42, 44 and 46, respectively. The apertures 42, 44 and 46 extendcompletely through the terminal portions 16 and 18. That is, theapertures extend from the body of the belt on one side of the seam,across the folded over portions 16 and 18 and into the body of the belton the other side of the seam.

The segmented cable 28 is in the form of a series of flexiblespaced-apart rods or pins in axial alignment with each other. Each ofthese rods is relatively short, when compared with the transversedimension of the belt, and is of a length not greater than andpreferably substantially coextensive with the transverse dimension ofthe adjacent seam segment. The rods are separated from each other by theapertures 42, 44 and 46 and are free to move toward and away from oneanother as the belt advances through the drying section of a papermachine.

Turning now to FIGURES 2 and 3, there is shown a belt 50 which includesa seam comprising a number of segments 52, 54, 56. Each of thesesegments is fabricated by overlapping the terminal portions 58 and 60 ofthe belt and joining them by stitching 62, 64. The terminal portions maybe further joined by an adhesive or by rivets, staples, lacing, etc.(not shown). The seam segments 52, 54 and 56 are separated from oneanother by apertures 66 and 68 which extend completely through theoverlapped portion formed by terminal portions 58 and 60 and into thebody, or single thickness portion, of the belt.

The apertures are preferably substantially diamondshaped as shown inFIGURES 1 and 2 but may, if desired, be of generally rectangularconfiguration and in some cases may be in the form of narrow slits.Also, the cooperating seam segments, at each end of the belt, whilepreferably disposed opposite one another as shown in FIGURE 1, may bestaggered with relation to one another as shown in FIGURE 4.

In FIGURE 4, the belt 70 is formed at its ends into seam segments 72,74, 76, 78, 80 and 82, formed by folding back terminal portions, such asterminal portion 84 of seam segments 72 and terminal portion 86 of seamsegment 78, onto themselves. The terminal portions are stitched in placeby stitching 88 and 90.

The seam segments are staggered apart from one an other forming slots92, 94, 96 and 98. The segments contain clipper hooks such as clipperhooks 100 in seam segment 72 and clipper hooks 102 in sea-m segment 78.The clipper hooks on oppositely disposed seam segments are interleavedand joined by a cable 104. Because the clipper hooks 100 and 102 are ofsuch transverse dimension that a space exists between them, each of theseam segments is free to expand and contract, extend and return, in thetransverse direction. The embodiment of FIGURE 4 is particularly useful,because it retains the cable 104 in continuous form and so expeditesconnection of the belt ends.

Turning now to FIGURE 5, there is shown another embodiment of thepresent invention in which a flap in the. form of a cover tape 110 isjoined to the belt as described above with regard to FIGURE 1. The tape110 is joined by stitching 112 to the seam segment 14 on the sideopposite the folded over terminal portion 18 and is arranged to coverthe clipper hooks 24 and 26 so as to provide a smooth surface for thepaper being transported. The belt and paper move in the direction of thearrow. Ideally, the transverse dimensions of the apertures 42, 44 and 46are such that the apertures are reduced in size to a disappearing pointduring operation due to the longitudinal stress applied, thermalconditions, etc.

The terms and expressions which have been employed are used as terms ofdescription and not of limitation, and there is no intention in the useof such terms and expressions of excluding any equivalents of thefeatures shown and described, or portions theerof, but it is recognizedthat various modifications are possible within the scope of theinvention claimed.

What is claimed is:

1. A drier belt end fastening construction comprising, in combination, adrier belt having a pair of end portions, joining means forinterconnecting said end portions to form a seam for said drier belt,and a narrow flap affixed to a surface of. said drier belt in positionto cover s-aid joining means, said seam including a plurality ofapertures extending through said end portions, said joining means andsaid flap, whereby the seam is free to conform to the cross machinedimension of the body of the belt and wrinkling and puckering areavoided.

2. The method of reducing wrinkling and puckering in a belt formed froma fiat woven fabric and having a seam which differs substantially fromthe body of the belt in ability to conform to dimensional changesresulting from stresses occurring during operation comprising dividingthe seam into a plurality of discrete segments, successive segmentsbeing spaced apart from one another at predetermined intervals byremoving portions of the seam, whereby the segments are free to movedifferentially with respect to each other and to conform to the positionof the adjacent body of the belt, to thereby substantially eliminatewrinkling and puckering.

3. A method of forming an improved clipper scam in a papermakers drierbelt comprising installing a clipper seam in the drier belt, andthereafter removing predetermined portions of said seam in order todivide said seam into a plurality of scam segments, the seam segmentsbeing free to move differentially with respect to each other and toconform to the position of the adjacent body of the belt, to therebysubstantially eliminate wrinkling and puckering.

4. In a papermakers drier belt made from a flat material having a bodyportion and end portions which are joined together to render said beltendless, said end portions being substantially different in theirresponse to environmental changes than said body portion, theimprovement comprising a plurality of discrete seam segments disposed atspaced intervals along each of said end portions in the transversedirection of said belt, said seam segments being defined by aperturesdisposed between adjacent segments, each of said apertures extendinglongitudinally with respect to the belt substantially entirely across atleast one of said end portions, said apertures tending to compensate fordiffering responses of said end portions and said body portion toenvironmental changes.

5. In a papermakers drier belt made from a flat material having a bodyportion and end portions which are joined together to render said beltendless, said end portions being reinforced and having a substantiallydifferent response to environmental changes than said body portion, theimprovement comprising a plurality of discrete seam segments disposed atspaced intervals along each of said end portions in the transversedirection of said belt, said seam segments being defined by aperturesdisposed between adjacent segments, each of said apertures extendinglongitudinally with respect to the belt substantially entirely acrossthe reinforcement on at least one of said end portions, said aperturestending to compensate for differing responses of said end portionsandsaid body portion to environmental changes.

6. In a papermakers drier belt made from a fiat material having a bodyportion and two ends which are joined together to render said beltendless, said ends being turned over to overlap said body portion andthereby form end portions which are substantially different in theirresponse to environmental changes than said body portion, theimprovement comprising a plurality of discrete seam segments disposed atspaced intervals along each of said end portions in the transversedirection of said belt, said seam segments being defined by aperturesdisposed between adjacent segments, each of said apertures extendinglongitudinally with respect to the belt substantially entirely across atleast one of said turned over end portions, said apertures tending tocompensate for differing responses of said end portions and said bodyportion to environmental changes.

7. In a papermakers drier belt of the character set forth in claim 6,each of said apertures extending longitudinally with respect to saidbelt completely across at least one of said turned over end portions.

8. In a paperm'akers drier belt of the character set forth in claim 6,each of said apertures on one of said end portions being opposite anaperture on the other end portion.

9. In a papermakers drier belt made from a fiat material having a bodyportion and end portions which are joined together to render said beltendless, said end portions being substantially different in theirresponse to environmental changes than said body portion, theimprovement comprising a plurality of discrete seam segments disposed atspaced intervals along each of said end portions in the transversedirection of said belt, the individual seam segments being free to movetransversely with relation to one another, said seam segments beingdefined by apertures disposed between adjacent segments, each of saidapertures extending longitudinally with respect to the beltsubstantially entirely across at least one of said end portions, saidapertures tending to compensate for difiering responses of said endportions and said body portion to environmental changes.

10. In a papermakers drier belt made from a flat material having a bodyportion and end portions which are joined together to render said beltendless, said end portions being substantially different in theirresponse to environmental changes than said body portion, theimprovement comprising joining means for interconnecting said endportions, a narrow flap affixed to a surface of said drier belt inposition to cover said joining means, and a plurality of discrete seamsegments disposed at spaced intervals along each of said end portions inthe transverse direction of said belt, said seam segments being definedby apertures disposed between adjacent segments and extending throughsaid end portions, said joining means and said flap, each of saidapertures extending longitudinally with respect to the beltsubstantially entirely across at least one of said end portions, saidapertures tending to compensate for differing responses of said endportions and said body portion to environmental changes.

11. In a papermakers drier belt made from a flat material having a bodyportion and end portions which are joined together to render said beltendless, said end portions being substantially diiferent in theirresponse to environmental changes than said body portion, theimprovement comprising a plurality of discrete seam segments disposed atspaced intervals along each of said end portions in the transversedirection of said belt, joining means including a series of interleavedclipper hooks affixed to each of said seam segments and a plurality ofcomparatively short rods extending through said clipper hooks tointerconnect said segments, the individual seam segments being free tomove transversely with relation to one another, said seam segments beingdefined by apertures disposed between adjacent segments, each of saidapertures extending longitudinally with respect to the beltsubstantially entirely across at least one of said end portions, saidapertures tending to compensate for differing responses of said endportions and said body portion to environmental changes.

References Cited by the Examiner UNITED STATES PATENTS 1,506,489 8/1924Kiefer 2433 2,066,974 1/1937 Hindle et al 24-33 2,454,224 11/1948 Shook24-33 2,873,494 2/1959 Santos 2433 2,932,340 4/1960 Poeschl 742323,106,941 10/1963 Plummer 24205.16 X

WILLIAM F'ELDMAN, Primary Examiner.

MILTON S. MEHR, Examiner.

6. IN A PAPERMAKERS'' DRIER BELT MADE FROM A FLAT MATERIAL HAVING A BODYPORTION AND TWO ENDS WHICH ARE JOINED TOGETHER TO RENDER SAID BELTENDLESS, SAID ENDS BEING TURNED OVER TO OVERLAP SAID BODY PORTION ANDTHEREBY FORM END PORTIONS WHICH ARE SUBSTANTIALLY DIFFERENT IN THEIRRESPONSE TO ENVIRONMENTAL CHANGES THAN SAID BODY PORTION, THEIMPROVEMENT COMPRISING A PLURALITY OF DISCRETE SEAM SEGMENTS DISPOSED ATSPACED INTERVALS ALONG EACH OF SAID END PORTIONS IN THE TRANSVERSEDIRECTION OF SAID BELT, SAID SEAM SEGMENTS BEING DEFINED BY APERTURESDISPOSED BETWEEN ADJACENT SEGMENTS, EACH OF SAID APERTURES EXTENDINGLONGITUDINALLY WITH RESPECT TO THE BELT SUBSTANTIALLY ENTIRELY ACROSS ATLEAST ONE OF SAID TURNED OVER END PORTIONS, SAID APERTURES TENDING TOCOMPENSATE FOR DIFFERING RESPONSES OF SAID END PORTIONS AND SAID BODYPORTION OF ENVIRONMENTAL CHANGES.